1qln



STRUCTURE OF A TRANSCRIBING T7 RNA POLYMERASE INITIATION COMPLEX

Overview
The structure of a T7 RNA polymerase (T7 RNAP) initiation complex captured transcribing a trinucleotide of RNA from a 17-base pair promoter DNA containing a 5-nucleotide single-strand template extension was determined at a resolution of 2.4 angstroms. Binding of the upstream duplex portion of the promoter occurs in the same manner as that in the open promoter complex, but the single-stranded template is repositioned to place the +4 base at the catalytic active site. Thus, synthesis of RNA in the initiation phase leads to accumulation or "scrunching" of the template in the enclosed active site pocket of T7 RNAP. Only three base pairs of heteroduplex are formed before the RNA peels off the template.

Features
View of the nucleic acid (blue: nontemplate strand; cyan: template strand; red:RNA)

About this Structure
1QLN is a Single protein structure of sequence from Enterobacteria phage t7. Full crystallographic information is available from OCA.

Reference
Structure of a transcribing T7 RNA polymerase initiation complex., Cheetham GM, Steitz TA, Science. 1999 Dec 17;286(5448):2305-9. PMID:10600732

Page seeded by OCA on Sat May 3 06:25:17 2008